Wind turbines have been around for several hundred years. Initially, these devices were used to grind grains or to move surface water, then to pump water from underground aquifers. A few decades ago, technology advanced to the point that wind turbines were being used to drive generators and alternators for the production of electricity. Commercial (large scale) wind farms are now quite common around the globe. This technology has since found its way into the residential (small scale) applications. Until recently, horizontal axis wind turbines (HAWTs) were the only platforms being developed. Now, several styles of vertical axis wind turbines (VAWTs) are being manufactured.
Over the last several decades, the major improvements of the horizontal platforms have been limited to the materials used in manufacturing and the generators and alternators. The basic design of the horizontal platform turbine blades has not changed. The challenge in the wind turbine industry has always been to create more positive force than negative force on the opposing blades or fins of the turbine.
Currently available products, while evolving, are lacking in several ways. Existing HAWT and VAWT platforms require a large footprint. Existing HAWT and VAWT platforms have negative environmental impacts such as noise pollution, wildlife hazards and aesthetic issues. However, the greatest problem with existing HAWT and VAWT platforms is the passive nature of the designs. Generally, when wind encounters a turbine, there are three possible outcomes: (1) the wind is captured; (2) the wind is shed; or (3) the wind has a neutral impact. If the wind is captured, it can have either a positive impact, turning the blades and activating the generator, or a negative impact, pushing the blades in the opposing direction and affecting the ability of the turbine to rotate in a positive direction.
Existing HAWT and VAWT platforms do not direct wind. Rather, existing designs allow wind to make contact with the capture blades and the shed or neutral blades at the same time. The wind impact on the shed and neutral blades can generate momentary negative force to the shaft that turns the blade in the opposite of the desired direction. This negative force fights against the positive force and desired rotational direction, which in turn diminishes the speed and torque potential of the turbine as a whole and creates a pulsing affect in the rpm speed and energy production levels. Typical VAWTs create positive and negative forces that are initially equal in exposure. During rotation, VAWT blades move into positions around the axis that create more negative force exposure and potential on the shed side than positive. When transitioning from the equal exposure to the greater negative exposure the fins on each side of rotation axis fight against each other to turn the turbine in two different directions, creating a pulsing affect in energy production. The capture side exposure is increased by its shape, which captures more wind than it deflects, and the shed side deflects more air than it captures, thereby forcing the turbine to turn in the positive direction. But as long as the shed side creates momentary or constant capture surfaces in the shed position, an ever-present choking or braking affect is created. This braking affect reduces the potential of positive forces and directional speed (rpms), thereby limiting the production of power from the typical VAWT. The transition between more and less negative forces creates the fast and slow pulsing actions of the turbine head in a constant wind speed.
These characteristics of typical VAWTs limit the production of converted torque and power, slowing down the acceptance and application of VAWTs as viable energy alternatives compared to HAWT systems. Currently both VAWT and HAWT turbines must be very large in size to produce a viable level of torque to turn a large generator and therefore are very demanding on the environment, both by creating large footprints and by having unacceptable aesthetic values.
The foregoing example of the related art and limitations related therewith are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification and a study of the drawings.